1. From the Arrhythmia Unit and Electrophysiology Laboratories (P.D.B., F.B., D.T., N.T., P.V., C.B., F. Petracca, G.M.), Heart Surgery Unit (S.B., F.M., O.A.), Department of Cardiology and Cardiothoracic Surgery, and Anesthesia and Intensive Care (F. Pappalardo, A.Z.), Ospedale San Raffaele, Milan, Italy; and Cardiac Arrhythmia Research Centre, Centro Cardiologico Monzino, IRCCS, Milan, Italy (C.C.).